Phacoemulsification has become the preferred form of cataract, i.e. a cloudy eye lens, removal. One of the main advantages of phacoemulsification is, that only a small incision into the cornea or sclera of an eye is needed to remove the cataract. Furthermore, the removal of the cataract can be done very quickly. After the cataract is removed, an intraocular lens is inserted to replace the original lens.
The phacoemulsification technique uses a hand held microsurgical tool known as phacoemulsifier. This phacoemulsifier comprises a handpiece and a small diameter needle with a tip to be inserted into the small incision of the eye. The needle and therefore the tip are vibrated by an ultrasonic source. It breaks the cataract into small fragments and pieces, which are sucked out through the same tip in a controlled manner. The tip is therefore designed for emulsifying, fragmenting and/or cutting tissue and also comprises a central hollow bore or lumen for the suction or aspiration of the fragments.
During the procedure, an irrigation solution is introduced to maintain the pressure and to prevent the eye from collapsing. In order to introduce the irrigation solution, the needle is usually covered by a sleeve and the solution flows via the space between this sleeve and the needle. The solution is therefore also used to cool the tip, which is heating up during the phacoemulsification.
Usually, the needle and often the handpiece must be changed after the removal of the cataract nucleus in order to remove the residual cortex. It takes time to change the handpiece and the continuation of the surgery is disrupted.
U.S. Pat. No. 5,653,724 discloses a phacoemulsification needle which is angled to provide more comfortable ergonomic angle during phacoelmulsification and lens cortex removal. This angled needle is also considered to produce less heat when emulsifying the lens. Another angled phacoemulsification needle with a concentric sleeve is disclosed in U.S. Pat. No. 5,993,409.
Different shapes of phacoemulsification needles with slits, a second infusion hole and/or with increased outside diameter at the distal end of the needle body and the needles being surrounded by sleeves are described in U.S. Pat. No. 5,989,209, U.S. Pat. No. 6,159,175, EP-A-1'103'238, WO 00/74615 and US 2002/0099325.
Other techniques for cataract removal use laser energy to remove the cataract. A laser/aspiration probe is used for breaking and removing the lens. A separate infusion or irrigation probe is used for the irrigation solution.